Angle estimation with multi-frame processing for radar on mobile devices

ABSTRACT

An electronic device includes a processor operably connected to a radar transceiver. The processor is configured to transmit, via the radar transceiver, radar signals to detect an object. The processor is also configured to detect the object using a single radar frame or multiple radar frames from the radar signals. The processor is further configured to determine whether to use the single radar frame or the multiple radar frames based on motion of the object for angle identification between the object and the electronic device. Additionally, the processor is configured to identify the angle using the single radar frame based on a determination to use the single radar frame or the multiple radar frames based on a determination to use the multiple radar frames. The processor is also configured to modify radio frequency exposure levels based on the angle of the object relative to the electronic device.

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 63/215,039 filed on Jun. 25, 2021.The above-identified provisional patent application is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates generally to electronic devices. Morespecifically, this disclosure relates to angle estimation withmulti-frame processing for radar on mobile devices.

BACKGROUND

The use of mobile computing technology such as a portable electronicdevice has greatly expanded largely due to usability, convenience,computing power, and the like. One result of the recent technologicaldevelopment is that electronic devices are becoming more compact, whilethe number of functions and features that a given device can perform isincreasing. For example, certain electronic devices not only providevoice call services or internet browsing using a mobile communicationnetwork but can also offer radar capabilities.

5th generation (5G) or new radio (NR) mobile communications is recentlygathering increased momentum with all the worldwide technical activitieson the various candidate technologies from industry and academia. Thecandidate enablers for the 5G/NR mobile communications include massiveantenna technologies, from legacy cellular frequency bands up to highfrequencies, to provide beamforming gain and support increased capacity,new waveform (e.g., a new radio access technology (RAT)) to flexiblyaccommodate various services/applications with different requirements,new multiple access schemes to support massive connections, and so on.With the increase of mobile communication, care must be taken tominimize radio frequency exposure to the user of the electronic device.

SUMMARY

This disclosure relates to angle estimation with multi-frame processingfor radar on mobile devices.

In one embodiment, electronic device is provided. The electronic deviceincludes a radar transceiver and a processor. The processor is operablyconnected to the radar transceiver. The processor is configured totransmit, via the radar transceiver, radar signals to detect an objectwithin regions expanding from electronic device. The processor is alsoconfigured to detect the object using a single radar frame or multipleradar frames from the radar signals. The processor is further configuredto determine whether to use the single radar frame or the multiple radarframes based on motion of the object for angle identification betweenthe object and the electronic device. Additionally, the processor isconfigured to identify the angle between the object and the electronicdevice using (i) the single radar frame based on a determination to usethe single radar frame or (ii) the multiple radar frames based on adetermination to use the multiple radar frames. The processor is alsoconfigured to modify radio frequency exposure levels at one or more ofthe regions based on the angle of the object relative to the electronicdevice.

In another embodiment, a method is provided. The method includestransmitting radar signals to detect an object within regions expandingfrom electronic device. The method also includes detecting the objectusing a single radar frame or multiple radar frames from the radarsignals. The method further includes determining whether to use thesingle radar frame or the multiple radar frames based on motion of theobject for angle identification between the object and the electronicdevice. Additionally, the method includes identifying the angle betweenthe object and the electronic device using (i) the single radar framebased on a determination to use the single radar frame or (ii) themultiple radar frames based on a determination to use the multiple radarframes. The method also includes modifying radio frequency exposurelevels at one or more of the regions based on the angle of the objectrelative to the electronic device.

In yet another embodiment a non-transitory computer readable mediumembodying a computer program is provided. The computer programcomprising computer readable program code that, when executed by aprocessor of an electronic device, causes the processor to transmitradar signals to detect an object within regions expanding fromelectronic device; detect the object using a single radar frame ormultiple radar frames from the radar signals; determine whether to usethe single radar frame or the multiple radar frames based on motion ofthe object for angle identification between the object and theelectronic device; identify the angle between the object and theelectronic device using (i) the single radar frame based on adetermination to use the single radar frame or (ii) the multiple radarframes based on a determination to use the multiple radar frames; andmodify radio frequency exposure levels at one or more of the regionsbased on the angle of the object relative to the electronic device.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller may beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items may be used,and only one item in the list may be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example communication system according toembodiments of this disclosure;

FIG. 2 illustrates an example electronic device according to embodimentsof this disclosure;

FIG. 3A illustrates an example architecture of a monostatic radar signalaccording to embodiments of this disclosure;

FIG. 3B illustrates an example frame structure according to embodimentsof this disclosure;

FIG. 3C illustrates an example detailed frame structure according toembodiments of this disclosure;

FIGS. 3D and 3E illustrates example pulse structures according toembodiments of this disclosure;

FIG. 4A illustrates a diagram of an electronic device with multiplefield of view regions corresponding to beams according to embodiments ofthis disclosure;

FIG. 4B illustrates a signal processing diagram for controlling radiofrequency (RF) exposure according to embodiments of this disclosure;

FIGS. 4C and 4D illustrate processes for RF level exposure modificationsaccording to embodiments of this disclosure;

FIG. 5A illustrates a method for beam level exposure management based onobject detection according to embodiments of this disclosure;

FIG. 5B illustrates a method for object detection according toembodiments of this disclosure; for object detection

FIG. 5C illustrates a diagram of an example result of processing twoframes for object detection when the object is moving fast according toembodiments of this disclosure;

FIGS. 6-12 illustrate example methods for determining a number of framesfor angle estimation according to embodiments of this disclosure; and

FIG. 13 illustrates an example method for modifying radio frequencyexposure levels based on an identified angle between an electronicdevice and an object according to embodiments of this disclosure.

DETAILED DESCRIPTION

FIGS. 1 through 13 , discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably-arranged system or device.

To meet the demand for wireless data traffic having increased sincedeployment of the fourth generation (4G) communication systems, effortshave been made to develop and deploy an improved 5th generation (5G) orpre-5G or new radio (NR) communication system. Therefore, the 5G orpre-5G communication system is also called a “beyond 4G network” or a“post long term evolution (LTE) system.”

The 5G communication system is considered to be implemented in higherfrequency (such as millimeter wave (mmWave)) bands, e.g., 28 GHz or 60GHz bands, so as to accomplish higher data rates or in lower frequencybands, such as 6 GHz, to enable robust coverage and mobility support. Todecrease propagation loss of the radio waves and increase thetransmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud RadioAccess Networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation and the like.

An electronic device, according to embodiments of the present disclosurecan include a user equipment (UE) such as a 5G terminal. The electronicdevice can also refer to any component such as mobile station,subscriber station, remote terminal, wireless terminal, receive point,vehicle, or user device. The electronic device could be a mobiletelephone, a smartphone, a monitoring device, an alarm device, a fleetmanagement device, an asset tracking device, an automobile, a desktopcomputer, an entertainment device, an infotainment device, a vendingmachine, an electricity meter, a water meter, a gas meter, a securitydevice, a sensor device, an appliance, and the like. Additionally, theelectronic device can include a personal computer (such as a laptop, adesktop), a workstation, a server, a television, an appliance, and thelike. In certain embodiments, an electronic device can be a portableelectronic device such as a portable communication device (such as asmartphone or mobile phone), a laptop, a tablet, an electronic bookreader (such as an e-reader), a personal digital assistants (PDAs), aportable multimedia player (PMP), an MP3 player, a mobile medicaldevice, a virtual reality headset, a portable game console, a camera,and a wearable device, among others. Additionally, the electronic devicecan be at least one of a part of a piece of furniture orbuilding/structure, an electronic board, an electronic signaturereceiving device, a projector, or a measurement device. The electronicdevice is one or a combination of the above-listed devices.Additionally, the electronic device as disclosed herein is not limitedto the above-listed devices and can include new electronic devicesdepending on the development of technology. It is noted that as usedherein, the term “user” may denote a human or another device (such as anartificial intelligent electronic device) using the electronic device.

Beamforming is an important factor when an electronic device (such as aUE) tries to establish a connection with a base station (BS). Tocompensate for the narrower analog beamwidth in mmWave, analog beamssweeping can be employed to enable wider signal reception ortransmission coverage for the UE. A beam codebook comprises a set ofcodewords, where a codeword is a set of analog phase shift values, or aset of amplitude plus phase shift values, applied to the antennaelements, in order to form an analog beam. FIG. 4A, described below,illustrates a UE equipped with two mmWave antenna modules or panelslocated on the left and the right edges of the UE. A beam managementprocedure is implemented at the UE to maintain the best antenna moduleas well as the corresponding best beam of the antenna module for signalreception and transmission by the UE. The UE may also use multipleantenna modules simultaneously, in which case the beam managementprocedure can determine the best beam of each antenna module for signalreception and transmission by the UE.

Embodiments of the present disclosure take into consideration thatbeamforming is a used for reliable mmWave communications but at the sametime beamforming also can cause a concern for radio frequency exposureon human body, beyond various governmental regulations. Beamforming istypically used at both the infrastructure or network side (such as atthe base station or the access point) and the UE side. The process ofbeamforming is to adjust the antenna weights such that the transmissionenergy is concentrated in some direction. This focus of energy can helpprovide strong link signal for communications, but at the same time thismeans more radiation power in that direction and could raise concern onthe exposure to body of the user. Due to such health concern, regulatorybodies (such as the Federal Communications Commission (FCC) in theUnited States of America) have sets of regulations and guidancegoverning such exposure. Exposure includes both exposure at lowfrequency (<6 GHz) and exposure at high frequency (>6 GHz). Powerdensity (PD) is used as the exposure metric at high frequency.

Exposure limit poses a challenge regarding 5G millimeter wave uplink(UL). As discussed above, narrow beams (formed by beamformingtechniques) are used for 5G millimeter wave operation, however,beamforming increases the PD and, consequently, the exposure. CertainmmWave communications take a very conservative measure to meet theexposure regulations. For example, one such approach is to use lowenough Equivalent Isotropically Radiated Power (EIRP) by adjusting theduty cycle and either (i) lowering the transmit (TX) power, (ii)lowering the antenna gain, or (iii) both lower the TX power and theantenna gain.

Embodiments of the present disclosure take into consideration that whilesuch a conservative measure can ensure regulatory compliance, it forcesthe communication module to operate at suboptimal link quality and thusthe electronic device cannot reap the potential for very high data rateservices. For example, some solutions (non-sensing solutions) assumeworst case exposure. Embodiments of the present disclosure take intoconsideration that to guard against exceeding the limit, using lowpower, using wide beams, or a combination thereof. Using low power orwide beams can limit UL quality in both coverage and throughput.

Accordingly, embodiments of the present disclosure relate to using radarto assess a situation by sensing the surroundings of the electronicdevice. By assessing the situation, the electronic device can avoid apessimistic TX power control. For example, a smart exposure controlsolution can keep exposure compliance while minimizing the opportunityloss for communication beamforming operations. Embodiments of thepresent disclosure describe using radar to both detect a body part anddetermine a direction that the body part is present. Upon detecting abody part and determining its location, the electronic device can managethe beams for communication to maintain regulatory RF exposurecompliance while operating at enhanced link quality.

Radar sensing can be used for ranging, angle or both. For example, whenradar is used for ranging only, the electronic device can determinewhether a human body part is present and adjust the TX power. Foranother example, when radar is used for ranging and angle, theelectronic device can determine whether a human body part is present andits approximate location and adjust the TX power, for beamforming, basedon the location of the human body part. For instance, the electronicdevice can reduce the TX power at or near the location of the human bodypart and increase the TX power at locations where the human body part isabsent. For yet another example, when radar is used for ranging andangle, the electronic device can determine whether a human body part ispresent and its approximate location and select one or more beams forbeamforming based on the location of the human body part. In thisexample, the angle information can be used to identify if the body partis within the main beam direction of certain beams.

Embodiments of the present disclosure take into consideration that theregulatory bodies limit exposure due to such health concern with respectto a human body and not inanimate objects. Accordingly, embodiments ofthe present disclosure relate to using radar to distinguish between ahuman body part and an inanimate object, such as a table. One way todistinguish body part from other objects (such as inanimate objects) isto rely on movement. For example, there are always some micro-movementof the live body (such as breathing cycles or some other involuntarymuscle activities). While micro-movements are a good identifier of ahuman body, it can be quite challenging to reliably detect these minormovements in a static setting as it may require a very long radar frameduration.

Embodiments of the present disclosure take into consideration that whilelonger processing frames are able to identify small movements of thehuman body, it can introduce ambiguity in angle estimation when the bodypart has a large motion. For example, if the object moves over a certainamount the electronic device may be unable to determine the angle thatthe object is relative to the electric device due to a smearing effect.Accordingly, embodiments of the present disclosure relate to determiningwhether to use a single radar frame or multiple radar frames fordetecting movement, performing angle estimation, and determining whetherthe object is a human body part or an inanimate object.

Embodiments of the present disclosure also relate to methods forindirectly assessing the speed of an object (also referred to as atarget) to select a duration to derive a spatial covariance matrix. Forexample, using long radar frames can improve the quality of the spatialcovariance matrix in terms of signal to noise ratio if the target staysrelatively static during the radar frame. It is noted that indirectlyassessing the speed of an object is used since certain embodiments ofthe present disclosure use non-uniform radar pulse spacing and the speedof the object may not be directly estimated. Additionally, embodimentsof the present disclosure describe performing angle estimation whenusing multiple-frame radar detection with non-uniform pulse spacing. Forexample, when the object is moving fast, embodiments of the presentdisclosure describe using a short frame duration. For another example,when the object is moving slow or remaining stationary (except formicro-movements), embodiments of the present disclosure describe using alonger frame (or multiple frames) for the spatial covariance matrix.

While the descriptions of the embodiments of the present discloser,describe a radar based system for object detection and motion detection,the embodiments can be applied to any other radar based and non-radarbased recognition systems. That is, the embodiments of the presentdisclosure are not restricted to radar and can be applied to other typesof sensors (such as an ultra-sonic sensor) that can provide both range,angle, speed measurements, or any combination thereof. It is noted thatwhen applying the embodiments of the present disclosure using adifferent type of sensor (a sensor other than a radar transceiver),various components may need to be tuned accordingly.

FIG. 1 illustrates an example communication system 100 in accordancewith an embodiment of this disclosure. The embodiment of thecommunication system 100 shown in FIG. 1 is for illustration only. Otherembodiments of the communication system 100 can be used withoutdeparting from the scope of this disclosure.

The communication system 100 includes a network 102 that facilitatescommunication between various components in the communication system100. For example, the network 102 can communicate IP packets, framerelay frames, Asynchronous Transfer Mode (ATM) cells, or otherinformation between network addresses. The network 102 includes one ormore local area networks (LANs), metropolitan area networks (MANs), widearea networks (WANs), all or a portion of a global network such as theInternet, or any other communication system or systems at one or morelocations.

In this example, the network 102 facilitates communications between aserver 104 and various client devices 106-114. The client devices106-114 may be, for example, a smartphone (such as a UE), a tabletcomputer, a laptop, a personal computer, a wearable device, a headmounted display, or the like. The server 104 can represent one or moreservers. Each server 104 includes any suitable computing or processingdevice that can provide computing services for one or more clientdevices, such as the client devices 106-114. Each server 104 could, forexample, include one or more processing devices, one or more memoriesstoring instructions and data, and one or more network interfacesfacilitating communication over the network 102.

Each of the client devices 106-114 represent any suitable computing orprocessing device that interacts with at least one server (such as theserver 104) or other computing device(s) over the network 102. Theclient devices 106-114 include a desktop computer 106, a mobiletelephone or mobile device 108 (such as a smartphone), a PDA 110, alaptop computer 112, and a tablet computer 114. However, any other oradditional client devices could be used in the communication system 100,such as wearable devices. Smartphones represent a class of mobiledevices 108 that are handheld devices with mobile operating systems andintegrated mobile broadband cellular network connections for voice,short message service (SMS), and Internet data communications. Incertain embodiments, any of the client devices 106-114 can emit andcollect radar signals via a measuring (or radar) transceiver.

In this example, some client devices 108-114 communicate indirectly withthe network 102. For example, the mobile device 108 and PDA 110communicate via one or more base stations 116, such as cellular basestations or eNodeBs (eNBs). Also, the laptop computer 112 and the tabletcomputer 114 communicate via one or more wireless access points 118,such as IEEE 802.11 wireless access points. Note that these are forillustration only and that each of the client devices 106-114 couldcommunicate directly with the network 102 or indirectly with the network102 via any suitable intermediate device(s) or network(s). In certainembodiments, any of the client devices 106-114 transmit informationsecurely and efficiently to another device, such as, for example, theserver 104.

Although FIG. 1 illustrates one example of a communication system 100,various changes can be made to FIG. 1 . For example, the communicationsystem 100 could include any number of each component in any suitablearrangement. In general, computing and communication systems come in awide variety of configurations, and FIG. 1 does not limit the scope ofthis disclosure to any particular configuration. While FIG. 1illustrates one operational environment in which various featuresdisclosed in this patent document can be used, these features could beused in any other suitable system.

FIG. 2 illustrates an example electronic device in accordance with anembodiment of this disclosure. In particular, FIG. 2 illustrates anexample electronic device 200, and the electronic device 200 couldrepresent the server 104 or one or more of the client devices 106-114 inFIG. 1 . The electronic device 200 can be a mobile communication device,such as, for example, a UE, a mobile station, a subscriber station, awireless terminal, a desktop computer (similar to the desktop computer106 of FIG. 1 ), a portable electronic device (similar to the mobiledevice 108, the PDA 110, the laptop computer 112, or the tablet computer114 of FIG. 1 ), a robot, and the like.

As shown in FIG. 2 , the electronic device 200 includes transceiver(s)210, transmit (TX) processing circuitry 215, a microphone 220, andreceive (RX) processing circuitry 225. The transceiver(s) 210 caninclude, for example, a RF transceiver, a BLUETOOTH transceiver, a WiFitransceiver, a ZIGBEE transceiver, an infrared transceiver, and variousother wireless communication signals. The electronic device 200 alsoincludes a speaker 230, a processor 240, an input/output (I/O) interface(IF) 245, an input 250, a display 255, a memory 260, and a sensor 265.The memory 260 includes an operating system (OS) 261, and one or moreapplications 262.

The transceiver(s) 210 can include an antenna array including numerousantennas. For example, the transceiver(s) 210 can be equipped withmultiple antenna elements. There can also be one or more antenna modulesfitted on the terminal where each module can have one or more antennaelements. The antennas of the antenna array can include a radiatingelement composed of a conductive material or a conductive pattern formedin or on a substrate. The transceiver(s) 210 transmit and receive asignal or power to or from the electronic device 200. The transceiver(s)210 receives an incoming signal transmitted from an access point (suchas a base station, WiFi router, or BLUETOOTH device) or other device ofthe network 102 (such as a WiFi, BLUETOOTH, cellular, 5G, LTE, LTE-A,WiMAX, or any other type of wireless network). The transceiver(s) 210down-converts the incoming RF signal to generate an intermediatefrequency or baseband signal. The intermediate frequency or basebandsignal is sent to the RX processing circuitry 225 that generates aprocessed baseband signal by filtering, decoding, and/or digitizing thebaseband or intermediate frequency signal. The RX processing circuitry225 transmits the processed baseband signal to the speaker 230 (such asfor voice data) or to the processor 240 for further processing (such asfor web browsing data).

The TX processing circuitry 215 receives analog or digital voice datafrom the microphone 220 or other outgoing baseband data from theprocessor 240. The outgoing baseband data can include web data, e-mail,or interactive video game data. The TX processing circuitry 215 encodes,multiplexes, and/or digitizes the outgoing baseband data to generate aprocessed baseband or intermediate frequency signal. The transceiver(s)210 receives the outgoing processed baseband or intermediate frequencysignal from the TX processing circuitry 215 and up-converts the basebandor intermediate frequency signal to a signal that is transmitted.

The processor 240 can include one or more processors or other processingdevices. The processor 240 can execute instructions that are stored inthe memory 260, such as the OS 261 in order to control the overalloperation of the electronic device 200. For example, the processor 240could control the reception of forward channel signals and thetransmission of reverse channel signals by the transceiver(s) 210, theRX processing circuitry 225, and the TX processing circuitry 215 inaccordance with well-known principles. The processor 240 can include anysuitable number(s) and type(s) of processors or other devices in anysuitable arrangement. For example, in certain embodiments, the processor240 includes at least one microprocessor or microcontroller. Exampletypes of processor 240 include microprocessors, microcontrollers,digital signal processors, field programmable gate arrays, applicationspecific integrated circuits, and discrete circuitry. In certainembodiments, the processor 240 can include a neural network.

The processor 240 is also capable of executing other processes andprograms resident in the memory 260, such as operations that receive andstore data. The processor 240 can move data into or out of the memory260 as required by an executing process. In certain embodiments, theprocessor 240 is configured to execute the one or more applications 262based on the OS 261 or in response to signals received from externalsource(s) or an operator. Example, applications 262 can include amultimedia player (such as a music player or a video player), a phonecalling application, a virtual personal assistant, and the like.

The processor 240 is also coupled to the I/O interface 245 that providesthe electronic device 200 with the ability to connect to other devices,such as client devices 106-114. The I/O interface 245 is thecommunication path between these accessories and the processor 240.

The processor 240 is also coupled to the input 250 and the display 255.The operator of the electronic device 200 can use the input 250 to enterdata or inputs into the electronic device 200. The input 250 can be akeyboard, touchscreen, mouse, track ball, voice input, or other devicecapable of acting as a user interface to allow a user in interact withthe electronic device 200. For example, the input 250 can include voicerecognition processing, thereby allowing a user to input a voicecommand. In another example, the input 250 can include a touch panel, a(digital) pen sensor, a key, or an ultrasonic input device. The touchpanel can recognize, for example, a touch input in at least one scheme,such as a capacitive scheme, a pressure sensitive scheme, an infraredscheme, or an ultrasonic scheme. The input 250 can be associated withthe sensor(s) 265, the radar transceiver 270, a camera, and the like,which provide additional inputs to the processor 240. The input 250 canalso include a control circuit. In the capacitive scheme, the input 250can recognize touch or proximity.

The display 255 can be a liquid crystal display (LCD), light-emittingdiode (LED) display, organic LED (OLED), active matrix OLED (AMOLED), orother display capable of rendering text and/or graphics, such as fromwebsites, videos, games, images, and the like. The display 255 can be asingular display screen or multiple display screens capable of creatinga stereoscopic display. In certain embodiments, the display 255 is aheads-up display (HUD).

The memory 260 is coupled to the processor 240. Part of the memory 260could include a RAM, and another part of the memory 260 could include aFlash memory or other ROM. The memory 260 can include persistent storage(not shown) that represents any structure(s) capable of storing andfacilitating retrieval of information (such as data, program code,and/or other suitable information). The memory 260 can contain one ormore components or devices supporting longer-term storage of data, suchas a read only memory, hard drive, Flash memory, or optical disc.

The electronic device 200 further includes one or more sensors 265 thatcan meter a physical quantity or detect an activation state of theelectronic device 200 and convert metered or detected information intoan electrical signal. For example, the sensor 265 can include one ormore buttons for touch input, a camera, a gesture sensor, opticalsensors, cameras, one or more inertial measurement units (IMUs), such asa gyroscope or gyro sensor, and an accelerometer. The sensor 265 canalso include an air pressure sensor, a magnetic sensor or magnetometer,a grip sensor, a proximity sensor, an ambient light sensor, abio-physical sensor, a temperature/humidity sensor, an illuminationsensor, an Ultraviolet (UV) sensor, an Electromyography (EMG) sensor, anElectroencephalogram (EEG) sensor, an Electrocardiogram (ECG) sensor, anIR sensor, an ultrasound sensor, an iris sensor, a fingerprint sensor, acolor sensor (such as a Red Green Blue (RGB) sensor), and the like. Thesensor 265 can further include control circuits for controlling any ofthe sensors included therein. Any of these sensor(s) 265 may be locatedwithin the electronic device 200 or within a secondary device operablyconnected to the electronic device 200.

In this embodiment, one of the one or more transceivers in thetransceiver 210 is a radar transceiver 270 that is configured totransmit and receive signals for detecting and ranging purposes. Theradar transceiver 270 can transmit and receive signals for measuringrange and speed of an object that is external to the electronic device200. The radar transceiver 270 can also transmit and receive signals formeasuring the angle a detected object relative to the electronic device200. For example, the radar transceiver 270 can transmit one or moresignals that when reflected off of a moving object and received by theradar transceiver 270 can be used for determining the range (distancebetween he object and the electronic device 200), the speed of theobject, the angle (angle between he object and the electronic device200), or any combination thereof.

The radar transceiver 270 may be any type of transceiver including, butnot limited to a radar transceiver. The radar transceiver 270 canincludes a radar sensor. The radar transceiver 270 can receive thesignals, which were originally transmitted from the radar transceiver270, after the signals have bounced or reflected off of target objectsin the surrounding environment of the electronic device 200. In certainembodiments, the radar transceiver 270 is a monostatic radar as thetransmitter of the radar signal and the receiver, for the delayed echo,are positioned at the same or similar location. For example, thetransmitter and the receiver can use the same antenna ornearly-co-located while using separate, but adjacent antennas.Monostatic radars are assumed coherent, such as when the transmitter andreceiver are synchronized via a common time reference. FIG. 3A, below,illustrates an example monostatic radar.

Although FIG. 2 illustrates one example of electronic device 200,various changes can be made to FIG. 2 . For example, various componentsin FIG. 2 can be combined, further subdivided, or omitted and additionalcomponents can be added according to particular needs. As a particularexample, the processor 240 can be divided into multiple processors, suchas one or more central processing units (CPUs), one or more graphicsprocessing units (GPUs), one or more neural networks, and the like.Also, while FIG. 2 illustrates the electronic device 200 configured as amobile telephone, tablet, or smartphone, the electronic device 200 canbe configured to operate as other types of mobile or stationary devices.

FIG. 3A illustrates an example architecture of a monostatic radar inaccordance with an embodiment of this disclosure. FIG. 3B illustrates anexample frame structure 340 in accordance with an embodiment of thisdisclosure. FIG. 3C illustrates an example detailed frame structure 350according to embodiments of this disclosure. FIGS. 3D and 3E illustratesexample pulse structures 360 and 370, respectively, according toembodiments of this disclosure. The embodiments of FIGS. 3A-3E are forillustration only and other embodiments can be used without departingfrom the scope of the present disclosure.

FIGS. 3A illustrates an electronic device 300 that includes a processor302, a transmitter 304, and a receiver 306. The electronic device 300can be similar to any of the client devices 106-114 of FIG. 1 , theserver 104 of FIG. 1 , or the electronic device 200 of FIG. 2 . Theprocessor 302 is similar to the processor 240 of FIG. 2 . Additionally,the transmitter 304 and the receiver 306 can be included within theradar transceiver 270 of FIG. 2 .

The transmitter 304 of the electronic device 300 transmits a signal 314to the target object 308. The target object 308 is located a distance310 from the electronic device 300. For example, the transmitter 304transmits a signal 314 via an antenna. In certain embodiments, thetarget object 308 correspond to a human body part. The signal 314 isreflected off of the target object 308 and received by the receiver 306,via an antenna. The signal 314 represents one or many signals that canbe transmitted from the transmitter 304 and reflected off of the targetobject 308. The processor 302 can identify the information associatedwith the target object 308, such as the speed the target object 308 ismoving and the distance the target object 308 is from the electronicdevice 300, based on the receiver 306 receiving the multiple reflectionsof the signals, over a period of time.

Leakage (not shown) represents radar signals that are transmitted fromthe antenna associated with transmitter 304 and are directly received bythe antenna associated with the receiver 306 without being reflected offof the target object 308.

In order to track the target object 308, the processor 302 analyzes atime difference 312 from when the signal 314 is transmitted by thetransmitter 304 and received by the receiver 306. It is noted that thetime difference 312 is also referred to as a delay, as it indicates adelay between the transmitter 304 transmitting the signal 314 and thereceiver 306 receiving the signal after the signal is reflected orbounced off of the target object 308. Based on the time difference 312,the processor 302 derives the distance 310 between the electronic device300, and the target object 308. Additionally, based on multiple timedifferences 312 and changes in the distance 310, the processor 302derives the speed that the target object 308 is moving.

Monostatic radar is characterized for its delayed echo as thetransmitter 304 of the radar signal and the receiver 306 of the radarsignal essentially are at the same location. In certain embodiments, thetransmitter 304 and the receiver 306 are co-located either by using acommon antenna or nearly co-located but use separate but adjacentantennas. Monostatic radars are assumed coherent such that thetransmitter 304 and the receiver 306 are synchronized via a common timereference.

A radar pulse is generated as a realization of a desired radar waveform,modulated onto a radio carrier frequency, and transmitted through apower amplifier and antenna, such as a parabolic antenna. In certainembodiments, the pulse radar is omnidirectional. In other embodiments,the pulse radar is focused into a particular direction. When the targetobject 308 is within the field of view of the transmitted signal andwithin a distance 310 from the radar location, then the target object308 will be illuminated by RF power density (W/m²), p_(t), for theduration of the transmission. Equation (1) describes the first order ofthe power density, p_(t).

$\begin{matrix}{p_{t} = {{\frac{P_{T}}{4\pi R^{2}}G_{T}} = {{\frac{P_{T}}{4\pi R^{2}}\frac{A_{T}}{\left( {\lambda^{2}/4\pi} \right)}} = {P_{T}\frac{A_{T}}{\lambda^{2}R^{2}}}}}} & (1)\end{matrix}$

Referring to Equation (1), P_(T) is the transmit power (W). G_(T)describes the transmit antenna gain (dBi) and A_(T) is an effectiveaperture area (m²). λ corresponds to the wavelength of the radar signal(m), and R corresponds to the distance 310 between the antenna and thetarget object 308. In certain embodiments, effects of atmosphericattenuation, multi-path propagation, antenna loss and the like arenegligible, and therefore not addressed in Equation (1).

The transmit power density impinging onto the target object 308 surfacecan cause reflections depending on the material, composition, surfaceshape and dielectric behavior at the frequency of the radar signal. Incertain embodiments, only direct reflections contribute to a detectablereceive signal since off-direction scattered signals can be too weak tobe received by at the radar receiver. The illuminated areas of thetarget with normal vectors pointing back at the receiver can act astransmit antenna apertures with directives (gains) in accordance withtheir effective aperture areas. Equation (2), below, describes thereflective back power.

$\begin{matrix}{P_{{ref}1} = {{\left. p_{t}A_{t}G_{t} \right.\sim p_{t}A_{t}r_{t}\frac{A_{t}}{\lambda^{2}/4\pi}} = {p_{t}{RSC}}}} & (2)\end{matrix}$

In Equation (2), P_(ref1) describes the effective isotropictarget-reflected power (W). The term, A_(t), describes the effectivetarget area normal to the radar direction (m²). The term r_(t) describesthe reflectivity of the material and shape, which can range from [0, . .. , 1]. The term G_(t) describes the corresponding aperture gain (dBi).RSC is the radar cross section (m²) and is an equivalent area thatscales proportional to the actual reflecting area-squared inverselyproportional with the wavelength-squared and is reduced by various shapefactors and the reflectivity of the material itself. Due to the materialand shape dependency, it is difficult to deduce the actual physical areaof a target from the reflected power, even if the distance 310 to thetarget object 308 is known.

The target reflected power at the receiver location results from thereflected power density at the reverse distance 310 collected over thereceiver antenna aperture area. Equation (3), below, describes thereceived target reflected power. It is noted that P_(R) is the receivedtarget reflected power (W) and A_(R) is the receiver antenna effectiveaperture area (m²). In certain embodiments, A_(R) is the same as A_(r).

$\begin{matrix}{P_{R} = {{\frac{P_{{ref}1}}{4\pi R^{2}}A_{R}} = {{P_{T} \cdot {RSC}}\frac{A_{T}A_{R}}{4\pi\lambda^{2}R^{4}}}}} & (3)\end{matrix}$

A radar system can be used as long as the receiver signal exhibitssufficient signal-to-noise ratio (SNR). The value of SNR depends on thewaveform and detection method. Equation (4), below, describes the SNR.It is noted that kT is the Boltzmann constant multiplied by the currenttemperature. B is the radar signal bandwidth (Hz). F is the receivernoise factor which is a degradation of the receive signal SNR due tonoise contributions of the receiver circuit itself.

$\begin{matrix}{{SNR} = \frac{P_{R}}{{kT} \cdot B \cdot F}} & (4)\end{matrix}$

When the radar signal is a short pulse of duration or width, T_(p), thedelay or time difference 312 between the transmission and reception ofthe corresponding echo is described in Equation (5). τ corresponds tothe delay between the transmission and reception of the correspondingecho and equal to Equation (5). c is the speed of light propagation inthe air. When there are multiple targets at different distances,individual echoes can be distinguished only if the delays differ by atleast one pulse width. As such, the range resolution of the radar isdescribed in Equation (6). A rectangular pulse of a duration T_(P)exhibits a power spectral density as described in Equation (7) andincludes a first null at its bandwidth as shown in Equation (8). Therange resolution of a radar signal is connected with the bandwidth ofthe radar waveform is expressed in Equation (9).

τ=2R/c   (5)

ΔR=cΔτ/2=cT _(P)/2   (6)

P(f)˜(sin (πfT _(p))/(πfT _(p)))²   (7)

B=1/T _(P)   (8)

ΔR=c/2B   (9)

Depending on the radar type, various forms of radar signals exist. Oneexample is a Channel Impulse Response (CIR). CIR measures the reflectedsignals (echoes) from potential targets as a function of distance at thereceive antenna module, such as the radar transceiver 270 of FIG. 2 . Incertain embodiments, CIR measurements are collected from transmitter andreceiver antenna configurations which when combined can produce amultidimensional image of the surrounding environment. The differentdimensions can include the azimuth, elevation, range, and Doppler.

The speed resolution (such as the Doppler resolution) of the radarsignal is proportional to the radar frame duration. Radar speedresolution is described in Equation (10), below.

$\begin{matrix}{{\Delta v} = \frac{\lambda}{2T_{{tx} - {frame}}}} & (10)\end{matrix}$

Here, λ is the wavelength of the operating frequency of the radar, andT_(tx-frame) is the duration of active transmission (simply called theradar frame duration here) of the pulses in the radar frame.

The example frame structure 340 of FIG. 3B illustrates an example rawradar measurement. The frame structure 340 describes that time isdivided into frames 342, where each frame has an active transmissionperiod and a silence period, denoted as frame spacing. During the activetransmission period, M pulses 344 may be transmitted. For example, theexample frame structure 340 includes frame 1, frame 2, frame 3, throughframe N. Each frame includes multiple pulses 344, such as pulse 1, pulse2 through pulse M.

In certain embodiments, different transmit and receive antennaconfigurations activate for each pulse or each frame. In certainembodiments, different transmit or receive antenna configurationsactivate for each pulse or each frame. It is noted that although theexample frame structure 340 illustrates only one frame type, multipleframe types can be defined in the same frame, where each frame typeincludes a different antenna configuration. Multiple pulses can be usedto boost the SNR of the target or may use different antennaconfigurations for spatial processing.

In certain embodiments, each pulse or frame may have a differenttransmit/receive antenna configuration corresponding to the active setof antenna elements and corresponding beamforming weights. For example,each of the M pulses in a frame can have different transmit and receiveantenna pair allowing for a spatial scan of the environment (such asusing beamforming), and each of the frames 342 all repeat the samepulses.

The example frame structure 340 illustrates uniform spacing betweenpulses and frames. In certain embodiments, any the spacing, evennon-uniform spacing, between pulses and frames can be used.

Long radar frames can be used to generate reliable detection of anobject even when there is only minor and weak movement, since there is ahigher chance that movement will occur during a long frame. To minimizethe cost of using long radar frames, embodiments of the presentdisclosure describe processing multiple radar frames to increase theradar observation time while keeping the same or similar effective radartransmission cycle.

FIG. 3C illustrates a detailed frame structure 350 according toembodiments of this disclosure. The detailed frame structure 350 can besimilar to the frames 342 of FIG. 3B. The detailed frame structure 350includes frames 352 a, 352 b, and 352 c. Each frame, such as frame 352a, has a specific transmission interval 354. Similarly, each of theframes are separated by a frame spacing interval, such as the framespacing interval 356 and the frame spacing interval 356 a. For example,frame 352 a and frame 352 b are separated by the frame spacing interval356. Similarly, frame 352 b is separated from the frame 352 c by framespacing interval 356 a. The frame spacing interval 356 and the framespacing interval 356 a can be the same or different time durations.

In certain embodiments, the frame transmission interval 354 is shorterthan the frame spacing interval 356. For example, the frame transmissioninterval 354 can be 0.2 seconds for each of the frames (such as frame N)and the frame spacing interval 356 can be 0.8 seconds. In this example,when processing two consecutive frames the effective radar frameincreases to 1.2 seconds (the duration of two of the frames which have atransmission interval of 0.2 seconds each, and the frame spacinginterval of 0.8 seconds), while the actual radar transmission remainsthe same. Similarly, when processing three consecutive frames theeffective radar frame increases to 2.2 seconds (the duration of three ofthe frames which have a transmission interval of 0.2 seconds each, andtwo frame spacings intervals which are 0.8 seconds each), while theactual radar transmission remains the same.

In certain embodiments, one or more radar frames can be used to generatereliable detection of a human body part even when there is only minorand weak movement. As described above RF exposure levels are monitoredfor human body parts. As such, human body part can be distinguished froman inanimate object (such as a table) based on movements of the objectitself. For example, if a single radar-frame does not detect a movingobject, embodiments of the present disclosure describe using multipleradar frames to detect the moving object. Upon determining that theobject moves, embodiments of the present disclosure describe identifyingthe angle of arrival of the object relative to the radar transmitter.The radar frames can include non-uniformly spaced radar pulses oruniformly spaced radar pulses.

For instance, if the radar measurements were conducted using multipleframes, where the transmission interval 354 of a frame is 0.2 second andthe frame spacing interval 356 is 0.8 seconds, the more frames that areprocessed can increase the ability of the electronic device to identifymotion of a detected object. For instance, using one frame to detectmotion the detection rate can be 54.5%. When using two frames to detectmotion the detection rate can increase to 97.6% and when using threeframes to detect motion the detection rate can increase to 100%. Assuch, the more frames that are used, where each frame is separated by aframe spacing interval 356, increases the likelihood that movement isdetected, where the movement indicates that a detected object is a humanbody part instead of an inanimate object. It is noted that if thedetected object is an inanimate object, the electronic device may notreduce the transmit power since there is no concern for RF exposure tothe inanimate object. In contrast, upon determining that the objectmoves, then electronic device may reduce the transmit power since thereis a concern for RF exposure.

FIGS. 3D and 3E illustrates example pulse structures 360 and 370according to embodiments of this disclosure. The pulse structure 360 ofFIG. 3D has a number of pulses, such as pulse 1 through pulse 5, whichare separated by a pulse spacing 364. A pulse interval 362 is the lengthof the transmission of a pulse and a subsequent pulse spacings 364.

The pulse structure 360 of FIG. 3D illustrates a special case of a framestructure. The pulse structure 360 illustrates the frame spacing asbeing the same as the pulse spacing 364. In this embodiment, there is noactual physical boundaries between the frames. This timing structureallows sliding window processing where the stride (how often to do theprocessing) could be selected accordingly. An illustrative example forsliding window 366 and 368 of three pulses with a stride of two is shownin FIG. 3D.

The pulse structure 370 of FIG. 3E illustrates a special case where thesampling of the pulses may not be uniform. For example, pulse 372 a isseparated from pulse 372 b by pulse spacing 374. Similarly, pulse 372 bis separated from pulse 372 c by pulse spacing 376. The pulse spacing374 and the pulse spacing 376 can be the same or different timedurations.

Using variable spacing between pulses and/or frames can increaseflexibility and provide coexistence with other systems. For example,consider a 5G system setting, the radar may be constrained by the 5Gscheduler on when the radar could operate. By allowing variable spacing,the radar can transmit whenever allowed or not impacting the 5Gscheduled time. For another example, consider a WiFi-like system thatimplements a carrier sensing-based solution. In such a case, theavailability of the medium is unknown a priori. The transmitter wouldhave to first listen for transmission in the medium before it cantransmit. This kind of uncertainty makes it difficult to guaranteeuniform sampling of the pulses and/or frames.

Although FIGS. 3A-3E illustrate electronic device 300 and radar signals,various changes can be made to FIGS. 3A-3E. For example, differentantenna configurations can be activated, different frame timingstructures can be used or the like. FIGS. 3A-3E do not limit thisdisclosure to any particular radar system or apparatus.

FIG. 4A illustrates a diagram 400 of an electronic device with multiplefield of view regions corresponding to beams according to embodiments ofthis disclosure. FIG. 4B illustrates a signal processing diagram 420 forcontrolling radio frequency (RF) exposure according to embodiments ofthis disclosure. FIGS. 4C and 4D illustrate processes 426 a and 426 b,respectively, RF level exposure modifications according to embodimentsof this disclosure. The embodiments of the diagram 400, the signalprocessing diagram 420, and the process 426 a, are for illustrationonly. Other embodiments can be used without departing from the scope ofthe present disclosure.

The diagram 400, as shown in FIGS. 4A illustrates an electronic device410. The electronic device 410 can be similar to any of the clientdevices 106-114 of FIG. 1 , the server 104 of FIG. 1 , the electronicdevice 200 of FIG. 2 , or the electronic device 300 of FIG. 3A.

The electronic device 410 can include one or more mmWave antenna modulesor panels on. The electronic device 410 can transmit multiple beamscorresponding to various regions such as region 415 a, 415 b, 415 c, 415d, 415 e, and 415 f (collectively regions 415). Each beam has a widthand a direction. To transmit the beams the electronic device 410 caninclude two or more mmWave antenna modules or panels such as an antenna.Other electronic devices can include less or more mmWave antenna modulesor panels, such as a single mmWave antenna module or panel.

An RF exposure engine can maintain exposure compliance while minimizingthe opportunity loss for communication beamforming operations. One wayto achieve such RF exposure control is for the device to be able to knowwhether there is exposure risk (or whether there is no exposure risk)based on detecting whether there is a body part of a human nearby withinone or more of the field-of-view (FoV) regions of the antennas or not.

The signal processing diagram 420 illustrates an example process forcontrolling RF exposure. The signal processing diagram 420 includesseveral information repositories, including a radar detection results424, a transmission margin 428, and transmission configuration history432. These information repositories can be similar to or included withinthe memory 260 of FIG. 2 . The signal processing diagram 420 alsoincludes a radar transceiver 422, which can be similar to the radartransceiver 270 of FIG. 2 . The signal processing diagram 420 furtherincludes transceiver 430 which can be similar to the transceiver 210 ofFIG. 2 .

The radar transceiver 422 transmits and receives radar signals. Thereceived radar signals are used to detect objects which are stored inthe radar detection results 424. The electronic device logs any detectedresults in the radar detection results 424. The transceiver 430 logs itsadopted transmission configuration such as the transmit power, the beamindex used, the duty cycle and the like to the TX configuration history432. Based on (i) whether an object is detected (as indicated in theradar detection results 424) and (ii) previous RF exposure levels (asindicated in the TX configuration history 432) the RF exposure engine426 estimate the worst case RF exposure and derive the transmissionmargin 428. The transmission margin 428 is a level of RF transmissionthat would not lead to RF exposure violation, which occurs when a useris exposed to RF above the margin.

It is noted that the update rate of the TX configuration and the radardetection may not be the same. For example, the update rate of the TXconfiguration could be almost instantaneous (or can practically assumeso), while radar detection could be done sporadically due to theconstraint on the radar transmission and/or the computational cost forrunning the radar detection procedure.

The RF exposure engine 426 can control RF exposure based on amodule-level or a beam-level based on radar capability. For example, ifthe radar cannot detect angle (such as when the electronic device has asingle antenna) or lacks enough resolution, the RF exposure engine 426may operate the module-level RF exposure management, illustrated in FIG.4C. If the radar has good range resolution and can estimate the angle ofthe object, the RF exposure engine 426 may operate using the beam-levelRF exposure management, illustrated in FIG. 4D.

FIG. 4C illustrates the process 426 a for the RF exposure engine 426 ofFIG. 4B to derive the transmission margin 428 to prevent RF exposureover a predefined limit regarding a module-level RF exposure.

For module-level RF exposure management, the RF exposure engine 426, instep 440 determines, whether a target is within the FoV. The FoV caninclude multiple regions on one side of the electronic device 410, suchas the regions 415 a-415 c. When the electronic device does not detectan object within the region 415 a-415 c (based on the results from theradar transmission), the RF exposure engine 426 in step 442 can notifythe mmWave communication module, (such as the transceiver 210 of FIG. 2or the transceiver 430 of FIG. 4B) that is it clear to transmit with nolimitations. Alternatively, when the electronic device detects an objectthat is classified as a human body part (based on the results from theradar transmission and movement of the object), that is within the areadefined by the region 415 a-415 c, then the RF exposure engine 426 instep 444 notifies the mmWave communication module, (such as thetransceiver 210 of FIG. 2 or the transceiver 430 of FIG. 4B) so thatmmWave communication module may reduce the transmit power, revert tousing less directional beam, or abort the transmission altogether if theexposure risk is too eminent.

FIG. 4D illustrates the process 426 b for the RF exposure engine 426 ofFIG. 4B to derive the transmission margin 428 to prevent RF exposureover a predefined limit regarding a beam-level RF exposure.

For the beam-level RF exposure management, the FoV of the module-levelRF is divided into smaller FoV regions (the granularity depends on theangle resolution of the radar and expected object (target) size), suchas the region 415 a. The operation is the same as the module-leveloperation, with the exception that here only when a target is detectedwithin a particular FoV region, such as the region 415 a that the RFexposure engine 426 would make adjustment for the affected beamsbelonging to that FoV region.

For example, the RF exposure engine 426, in step 450 determines whethera target is within the FoV. The FoV can correspond to different beamsillustrated by the different regions 415. When the electronic devicedoes not detect an object (or detects an object that is determined tonot be a human body part), the RF exposure engine 426 in step 452 cannotify the mmWave communication module, (such as the transceiver 210 ofFIG. 2 or the transceiver 430 of FIG. 4B) that is it clear to transmitwith no limitations. Alternatively, when the electronic device detectsan object, that is classified as a human body part, the electronicdevice determines, in step 454, which region the object is within. Basedon which of the one or more regions 415 a-415 f are blocked, the RFexposure engine 426 in step in step 456 a-456 n, notifies the mmWavecommunication module, (such as the transceiver 210 of FIG. 2 or thetransceiver 430 of FIG. 4B) so that mmWave communication module mayreduce the transmit power to the particular region, revert to using lessdirectional beam in the particular region, or abort the transmissionaltogether if the exposure risk is too eminent. For example, if the handof the user is detected in the region 415 a and no object is detected inthe regions 415 b-415 f, then the mmWave communication module may reducethe power or disable the 5G beams within the region 415 a whilemaintaining a higher transmit power in the regions 415 b-415 f withoutrisking any exposure concerns to the user.

Although FIGS. 4A-4D illustrates the electronic device 410, the signalprocessing diagram 420, and the processes 426 a and 426 b, variouschanges can be made to FIG. 4A-4D. For example, any number of antennascan be used to create any number of regions FIGS. 4A-4D does not limitthis disclosure to any particular radar system or apparatus.

FIG. 5A illustrates a method 500 for beam level exposure managementbased on object detection according to embodiments of this disclosure.FIG. 5B illustrates a method for object detection from step 520 of FIG.5A according to embodiments of this disclosure; for object detection.FIG. 5C illustrates a diagram 580 of an example result of processing twoframes for object detection when the object is moving fast according toembodiments of this disclosure. The method 500 is described asimplemented by any one of the client device 106-114 of FIG. 1 , theserver 104 of FIG. 1 , the electronic device 300 of FIG. 3A theelectronic device 410 of FIG. 4A and can include internal componentssimilar to that of electronic device 200 of FIG. 2 . However, the method500 as shown in FIG. 5A could be used with any other suitable electronicdevice and in any suitable system, such as when performed by theelectronic device 200. For ease of explanation, FIGS. 5A, 5B, and 5C aredescribed as being performed by the electronic device 200 of FIG. 2 .

The embodiments of the method 500 of FIG. 5A, the method of FIG. 5B, andthe diagram 580 of FIG. 5C are for illustration only. Other embodimentscan be used without departing from the scope of the present disclosure.

The method 500 of FIG. 5A describes processing a single radar frame. Themethod 500 first determines whether there is an object such as a humanbody part within the FoV of the radar, and then determines the rangesand angles of each detected human body for adjusting the RF exposurelevel relative to the location of the detected human body part. Themethod 500 is described as being performed once per radar frameinterval, however depending on the application requirements, systemconstraint, or the like, it could be desirable to select a differentprocessing interval than the radar frame interval. For example, theprocessing could be performed once per N radar frames.

In step 510, the electronic device 200 obtains radar measurements. Radarmeasurements are obtained based on a radar transceiver (such as theradar transceiver 270 of FIG. 2 ) transmitting radar signals andreceiving reflections of the radar signals. In certain embodiments, theradar measurements are obtained from an information repository (such asthe memory 260 of FIG. 2 ) which stores previously derived radarmeasurements.

In step 520, electronic device 200 performs a radar detection to detectan object from the radar measurements. Step 520 is described in detailin FIG. 5B, below. In step 540, the electronic device 200 determineswhether an object is detected. If no object is detected (or the detectedobject is not a human body part), then the electronic device 200declares that no object is detected, which is provided to the RFexposure engine 426 of FIG. 4B (step 570).

Alternatively, if a human body part is detected (as determined in step540), the electronic device 200 estimates the range and angle of theobject (step 560). For example, if there is at least one objectdetected, the range and angle of each object is identified. All detectedobjects along with their attributes (ranges and angles) are provided tothe RF exposure engine 426 of FIG. 4B (step 570). The RF exposure engine426 can reduce the transmission power, duty cycle, or abort thetransmission altogether for certain beams that correspond to theangle(s) of the detected objects. The RF exposure engine 426 can useother beam directions corresponding to regions where the object is notdetected without exposure risk.

FIG. 5B describes the step 520 of FIG. 5A in greater detail. Inparticular, FIG. 5B describes target detection based on single-frameprocessing. Moreover, FIG. 5B describes detecting a moving objectcorresponding to a human body part.

In step 522, the electronic device 200 obtains measurements from oneradar frame. The step 522 can obtain the radar measurements from step510 of FIG. 5A.

In step 524, the electronic device 200 identifies a Range-Amplitude (RA)map for each pulse of the obtained radar frame. For example, the rawradar measurements are processed (pulse-compression or takingfast-Fourier transform (FFT) for Frequency Modulated Continuous Wave(FMCW) radar) to compute the Complex Impulse Response (CIR) also knownas range FFT for FMCW radar, whose amplitude is the RA map. The RA mapis a one dimensional signal that captures the amplitude of the reflectedpower from the reflectors in the FoV of the radar for a finite set ofdiscrete range values (denoted as range tap or tap). This CIR iscomputed for each pulse separately.

In step 526, the electronic device 200 averages the CIRs from all thepulses within the radar frame to generate the zero-frequency (DC)component as measured by the current processed radar frame. The DCcomponent is the estimate of the reflection from all static objectswithin the radar's FoV. These static reflections include the leakage(the direct transmission from the radar TX to the radar RX and otherreflections off the parts of the radar equipped device) as well as otherstatic objects (relative to the radar) not part of the device housingthe radar. In step 528, the electronic device 200 removes (subtracts)the DC component from each pulse.

In step 530, the electronic device 200 averages all resulting RA's toidentify the amplitude of each range tap and averaged across all theCIRs. The resulting output is called the range profile, which provide ameasure of the amplitude of non-static objects within the radar's FoVfor each range tap. In step 532, the electronic device 200 performs theobject detection using the range profile by identifying the peaks of therange profile as targets. For example, the electronic device 200 detectsthe peaks in the range profile and compares the value at the peak with adetection threshold. The detection threshold can be set according to thenoise floor at the particular range tap. For example, the threshold canbe set to some number of times the power of the noise floor (such as 3dB or twice the power of the noise floor). This threshold could beselected to balance misdetection and false alarm rate.

As described above, body parts of a live human can be expected topossess some movements at all times. The movement can be typical bodymovement (such as intentional hand movement such as grabbing or reachingfor something or some unintentional ones such micro movement caused bythe muscle reflexes, and the like). Some of the micro movements could bedifficult to see visually because of the minor and weak nature of thosemovement. For radar the sensitivity of the detection of such movementdepends on the observation time of the radar signals (which is the radarframe duration in our case). For example, the longer the frame durationis the more sensitive the radar is to the minor movement. Accordingly,the objects being detected as described in FIG. 5B are non-staticobjects in order to detect a body part of a human to avoid exposing thebody part to RF exposure above a certain threshold.

Embodiments of the present disclosure describe using a processing framethat is long enough to provide a sensitivity level, such that body partsare detected with as low misdetection rate. Embodiments of the presentdisclosure take into consideration that by increasing the transmissioninterval 354 of FIG. 3C, can reduce the misdetection rate. However,increasing the transmission interval 354 is costly in that it increasesthe radar duty cycle to maintain the same (or similar) frame interval.Additionally, if the radar shares a wireless medium with other systems,a long frame transmission time may create a conflict between the radarand other wireless systems.

In certain embodiments, the processing frame duration can be increasedby virtually allowing overlap between the processing frames. This allowsfor the transmission interval 354 of a frame to not increase. Forexample, as shown in FIG. 3C, two radar frames can be used within oneprocessing frame interval (such as the processing intervals 358 a and358 b) to increase the observation time of the radar signals used forthe detection. With single frame processing, the observation of theradar signal within the processing frame is equal to the frame TXinterval. In contrast, by processing two (or more) frames, theprocessing interval is increased for the duration of each transmissioninterval 354 of a frame and the frame spacing interval 356 between twoframes. For example, by processing two radar frames, the observationtimes is described in Equation (11), below.

(frame TX interval)+(frame spacing)+(frame TX interval)=2×(frame TXinterval)+(frame spacing).   (11)

As described in Equation (11) and shown in the processing interval 358 aof FIG. 3C, the processing duration is not just the transmissioninterval 345 of two frames (such as frames 352 a and 352 b), rather theprocessing duration is increased due to the silence period in the framespacing (such as the frame spacing interval 356 a). Additionally,depending on the detection frequency (one detection per second or thelike) the frame spacing could be much larger than the frame TX interval.When the frame spacing is larger than the frame TX interval, the radarobservation time for the detection increases without increasing theradar duty cycle.

The electronic device 200 can determine whether to use a single frame ormultiple frames (two or more frames) in a processing interval fordetecting movement of the object in order to determine whether tomodifying the RF exposure level in area(s) corresponding to the detectedobject. FIGS. 6-12 describe various processes for determining whether touse a single frame or multiple frames (two or more frames).

For estimating the angle of the object, first a (spatial) covariancematrix of the object (target) has to be estimated. One way to estimatethe covariance matrix is by computing the sample average of the CIRafter subtracting the average (0-Doppler removal) at the detected tapindex. Equation (12) below defines X_(p) as the vector of CIR of thep-th pulse at the target tap after the average subtraction of all theradar RX antennas.

X_(p)=[X_(p) ¹, X_(p) ², . . . , X_(p) ^(R)]^(T)   (12)

Here, the radar has R receive antennas, and X_(p) ^(r) is the CIR afterthe average subtraction of the p-pulse received at the r RX antenna. Itis noted that in this notation X_(p) is a column vector of dimension R.P is the number of CIRs (or pulses) of the radar frame, and H is theconjugate transpose operator, then the covariance matrix can beestimated as described in Equation (13), below.

$\begin{matrix}{R_{xx} = {\frac{1}{p}{\sum_{p = 1}^{P}{X_{p}X_{p}^{H}}}}} & (13)\end{matrix}$

The difference between the single-frame and the multi-frame processingfor the angle estimation is in the number of pulses P used forestimation of R_(xx). Note that since the radar transmission timingstructure is fixed (the same pulse and frame intervals), using a largerP also means R_(xx) is averaged over a longer time duration. With thiscovariance matrix, various angle estimation methods can be used. Someexamples include the Bartlett beamforming, the Capon's beamforming (alsoknown as Minimum Variance Distortionless Response MVDR), MUltiple SIgnalClassification (MUSIC), and the like. These methods are what is calledthe spectrum-based solutions, where the angular spectrum P(θ) iscomputed and the peaks in P(θ) are the targets and the angles θcorresponding to those peaks are their respective angle estimates. Letα(θ) be the steering vector of the array (normalized), then the angularspectrum for the Bartlett beamforming is described in Equation (14),below. Capon's beamforming is described in Equation (15), below. ForMUSIC, beamforming is described in Equations (16) and 17, below.

$\begin{matrix}{{P(\theta)} = {{a(\theta)}^{H}R_{xx}{a(\theta)}}} & (14)\end{matrix}$ $\begin{matrix}{{P(\theta)} = \frac{1}{{a(\theta)}^{H}R_{xx}^{- 1}{a(\theta)}}} & (15)\end{matrix}$ $\begin{matrix}{R_{xx} = {{U_{s}\Lambda_{s}U_{s}^{H}} + {\sigma^{2}U_{n}U_{n}^{H}}}} & (16)\end{matrix}$ $\begin{matrix}{{{P(\theta)} = \frac{1}{{a(\theta)}^{H}\left( {U_{n}U_{n}^{H}} \right){a(\theta)}}},} & (17)\end{matrix}$

Here, in Equations (16) and (17) U_(s) and U_(n) are the signal and thenoise subspace of R_(xx), and Λ_(s) (diagonal matrix with eigen values)and σ² (a scalar) are their corresponding eigen values. These can beobtained by performing eigen decomposition of R_(xx).

In certain embodiments, the electronic device 200 determines whether touse a single frame (a current frame) or multi frame (the current frameand one or more additional previous frames) for estimating thecovariance matrix. There are two considerations in selecting the frameduration (either to use single frame or to use two frames) to estimatethe covariance matrix. The first consideration favors the use ofsingle-frame. The covariance matrix estimate as described above assumesthe location change of the object to be small (stay within the samerange tap) during the estimation of the covariance matrix. Thisassumption can be broken when using multi-frame processing, and thus theshorter one like the single-frame is preferred. The second reasoningfavors the use of the two frames. When the object's response is weak,the estimation of the covariance matrix will suffer from low SNR andthus longer averaging would help. In our case, the amplitude of thesignal is the one after the 0-Doppler removal, and thus the lowamplitude likely means that object has little movement and thus thesmearing effect due to averaging over longer duration is not of concern

For object angle estimation, the covariance matrix is first estimatedwhere this covariance matrix is obtained by sample-averaged from thepulses within the radar frame. The typical assumption is that themovement of the object during the frame is negligible that it will notaffect the estimation of the covariance matrix. However, withmulti-frame processing this is no longer true. An illustrative exampleof this issue is shown in the diagram 580 of FIG. 5C. In this example,the target (the hand) is moving away from the device during themeasurements. For example, at the first time measurement the hand is atposition 582, and at the second time measurement the hand moved toposition 584. Here, the radar frame interval can be about one secondwith active transmission time of around 0.2 seconds. The graph 590describes how using a single frame (the current frame) or multipleframes (the current frame and one or more previous frames) can provideincorrect position of the hand when the hand is moving. Here, in the onesecond between the first radar frame and the second radar frame, thehand can move several centimeters causing the detected radar peak tofall into a different range tap index (tap 14 as shown in FIG. 5D),denoted by line 594. In this particular example, if the two frames areused to estimate covariance matrix, it would detect the angle of thetarget at tap 11 (line 592), which is not an actual target but a pastimage of the hand. In this case, using the current frame (of duration of0.2 seconds) would provide the correct angle estimation and usingmulti-frame would provide an incorrect angle estimation.

Although FIGS. 5A and 5B illustrates one example for detecting a movingobject and estimating its location various changes may be made to FIGS.5A and 5B. For example, while shown as a series of steps, various stepsin FIG. 5A, FIG. 5B, or both could overlap, occur in parallel, or occurany number of times.

FIGS. 6-12 illustrate example methods for determining a number of framesfor angle estimation according to embodiments of this disclosure. Inparticular, FIG. 6 illustrates a method 600 for determining a number offrames for angle estimation based on a detection status. FIG. 7illustrates a method 700 for determining a number of frames for angleestimation based on a detection status and an amplitude of the detectedtarget. FIG. 8 illustrates a method 800 for determining a number offrames for angle estimation based on a detection status and a detectedtarget tap index. FIG. 9 illustrates a method 900 for determining anumber of frames for angle estimation based on a detection status, adetected target tap index, and an amplitude of the detected target. FIG.10 illustrates a method 1000 for determining a number of frames forangle estimation based on a detection status and a detected target tapindex. FIG. 11 illustrates a method 1100 for determining a number offrames for angle estimation using more than two frames. FIG. 12illustrates a method 1200 for determining a number of frames for angleestimation using three frames. The embodiments of the method 600 of FIG.6 , the method 700 of FIG. 7 , the method 800 of FIG. 8 , the method 900of FIG. 9 , the method 1000 of FIG. 10 , the method 1100 of FIG. 11 ,and the method 1200 of FIG. 12 are for illustration only. Otherembodiments can be used without departing from the scope of the presentdisclosure.

The methods 600, 700, 800, 900, 1000, 1100, and 1200 are described asimplemented by any one of the client device 106-114 of FIG. 1 , theserver 104 of FIG. 1 , the electronic device 300 of FIG. 3A theelectronic device 410 of FIG. 4A and can include internal componentssimilar to that of electronic device 200 of FIG. 2 . For ease ofexplanation, methods 600 through 1200 are described as being performedby the electronic device 200 of FIG. 2 .

The method 600 of FIG. 6 describes a process for determining whether touse a single frame or two frames for angle estimation based on detectionstatus. For example, if the object is detected by the current singleframe (such as when the current frame, denoted as d_(cur), is true),then the single radar frame is used for covariance matrix estimation.Otherwise, if the two frames detects the object (such as the currentframe and a previous frame), then the two frames are used for angleestimation. Note that in this case, when the object is detected by thesingle-frame processing, then the two-frame processing is skipped,reducing some computation cost.

In step 602, the electronic device 200 performs object detection using asingle radar frame. The single frame is a current frame representing theenvironment around the electronic device 200 at a current time instance.In step 604, the electronic device 200 determines whether an object isdetected from the single frame. If the electronic device 200 determinesthat an object is detected, then in step 606, the electronic device 200uses the current frame for angle estimation. Alternatively, if theelectronic device 200 determines that an object is not detected, then instep 608, the electronic device 200 performs target detection using twoframes. The two frames include the current frame and a previous frame.The previous frame can be the frame that immediately came before thecurrent frame. If an object is detected using the two frames, theelectronic device 200, in step 610, uses the two frames for angleestimation. It is noted that if no object is detected in step 608, theelectronic device 200 can notify the RF exposure engine 426 of FIG. 4B(such as described above in step 570 of FIG. 5A) that no objects aredetected indicating that there is no need to mitigate the RF exposurelevel.

In certain embodiments, if the object is detected (using either thecurrent frame or multiple frames), indicates that the peak has strongenough SNR such that an accurate angle between the electronic device andthe location of the object can be identified.

The method 700 of FIG. 7 describes a process for determining whether touse a single frame or two frames for angle estimation based on thedetection status and the amplitude of the detected target. The amplitudelevel corresponds to an amount of movement of a detected object.Therefore, if a single frame has a large amplitude, it indicates thatthe single frame is preferred for angle estimation to avoid a smearingeffect. Alternatively, if the single frame has a small amplitude, itindicates that movement is small or non-existent and therefore twoframes should be used to detect whether the object moves.

It is noted that the method 700 modifies the method 600 of FIG. 6 toinclude the amplitude of the detected object when the object is detectedusing a single (current) frame. For example, when the object is detectedby the current single frame, the amplitude is checked to see if it isstrong enough (the threshold for this could be the detection thresholdplus some positive offset). If the detected object has strong signal,the single-frame is used, otherwise two frames are used. The reason isthat if the detected peak by the single frame is strong, it means thatit corresponds to a fast movement, and thus it can be expected that thecovariance matrix estimated over a shorter duration has more fidelityand thus the single-frame is preferred. On the contrary, if the detectedobject is weak, there likely is little movement and thus the two-frameprocessing could be used to boost the SNR of the covariance matrixestimate.

In step 702, the electronic device 200 performs target detection using asingle frame. The single frame is a current frame representing theenvironment around the electronic device 200 at a current time instance.In step 704, the electronic device 200 determines whether an object isdetected from the single frame. If the electronic device 200 determinesthat an object is detected, then in step 706, the electronic device 200compares the amplitude of the detected object to a threshold. If theamplitude of the detected object is greater than the threshold, theelectronic device 200 uses the current frame for angle estimation (step708).

Alternatively, if the electronic device 200 determines that (i) anobject is not detected (in step 704) or (ii) the amplitude of thedetected object is less than or equal to the threshold (in step 706),then in step 710, the electronic device 200 performs target detectionusing two frames. The two frames include the current frame and aprevious frame. The previous frame can be the frame that immediatelycame before the current frame. If an object is detected using the twoframes, the electronic device, in step 712, uses the two frames forangle estimation. It is noted that if no object is detected in step 710,the electronic device 200 can notify the RF exposure engine 426 of FIG.4B (such as described above in step 570 of FIG. 5A) that no objects aredetected indicating that there is no need to mitigate the RF exposurelevels.

The method 800 of FIG. 8 describes a process for determining whether touse a single frame or two frames for angle estimation based on detectionstatus and detected target tap index. Instead of the amplitude (asdescribed in FIG. 7 above), another option is to use the detected tapindex for determining whether to use a single frame (a current frame) ortwo frames. Here, if an object is detected by single-frame (currentframe) processing, then the electronic device 200 also determineswhether the detected peak is the same for both single-frame andtwo-frame processing. If detected peak is the same for both single-frameand two-frame processing, then two frame would be used for angleestimation. If they are not, the single-frame process is used instead.Note that when they are not, it could be that there was some movementlarge enough to cause the object to change in the peak location and thusit is best to use a shorter frame for accurate angle estimation.

As used in FIG. 8 , the expression d_(cur) and d₂ are the detectionstatus of particular frames, which can be a true (indicating that thesingle (current) frame d_(cur) or the two frames detect the object) orfalse (indicating that the single (current) frame d_(cur) or the twoframes do not detect the object). Additionally, the expression p_(cur)is the tap index of the detected object of the single (current) frameand p₂ is the tap index of the detected object of from the two frames.

In step 802, the electronic device 200 determines whether the object isdetected using the single (current) frame or two frames (the currentframe and frame that preceded the current frame). If the object is notdetected in either of the single frame or the two frames, then theelectronic device 200, in step 804, determines that no object isdetected. The electronic device 200 can notify the RF exposure engine426 of FIG. 4B (such as described above in step 570 of FIG. 5A) that noobjects are detected indicating that there is no need to mitigate the RFexposure levels.

Alternatively, if the electronic device 200 determines that an object isdetected in either of the single (current) frame or two frames, then instep 806, the electronic device 200 determines whether an object isdetected from the single frame (when d_(cur) is true). If the electronicdevice 200 determines that an object is detected from the single frame,then in step 808, the electronic device 200 determines whether detectedpeak is the same for both single-frame and two-frame processing. Ifdetected peak is not the same for both single-frame and two-frameprocessing, then the electronic device 200 uses the current frame forangle estimation (step 810). If (i) the object is not detected in thecurrent frame (as determined in step 806, such as when the object isdetected using both the current frame and its previous frame) or (ii)the detected peak is the same for both single-frame and two-frameprocessing (as determined in step 808), then the electronic device 200,in step 812, uses the two frames for angle estimation.

The method 900 of FIG. 9 describes a process for determining whether touse a single frame or two frames for angle estimation based on thedetection status, the amplitude of the detected object, and the detectedobject tap index. It is noted that the method 900 combines variousaspects of the method 600 of FIG. 6 , the method 700 of FIG. 7 , and themethod 800 of FIG. 8 .

In this example, the amplitude of the object detected using the currentsingle-frame processing. If the amplitude is strong enough, then the SNRis not an issue so that averaging over the shorter single-frameprocessing should be sufficient and can save some processing power. Inthis case, the current single-frame is used for angle estimation andthere is no need to perform the two-frame processing (both for targetdetection and for angle estimation). If there is no object detected inthe current frame or if the amplitude of the detected object is notstrong enough by the single-frame processing, then two-frame targetdetection is conducted. For the case when the single-frame detects anobject, the peak index detected by the single-frame and the two-frameare compared. If they match, the two frames are used for angleestimation, otherwise the single-frame is used for angle estimation. Ifthe single-frame does not detect an object, then the two-frame objectdetection is performed, and if an object is detected, then the twoframes are used for angle estimation.

In step 902, the electronic device 200 performs target detection using asingle (the current) frame. In step 904, the electronic device 200determines whether an object is detected from the single (current)frame. If the electronic device 200 determines that an object isdetected using the current frame, then in step 906, the electronicdevice 200 compares the amplitude of the detected object to a threshold.If the amplitude of the detected object is greater than the threshold,the electronic device 200 uses the current frame for angle estimation(step 908).

If the electronic device 200 determines that an object is not detectedin the current frame (as determined in step 904), then in step 916 theelectronic device 200 performs target detection using two frames. Thetwo frames include the current frame and a previous frame. The previousframe can be the frame that immediately came before the current frame.If an object is detected using the two frames, the electronic device, instep 914, uses the two frames for angle estimation.

If the electronic device 200 determines that the amplitude of thedetected object is less than or equal to the threshold (as determined instep 906), then in step 910, the electronic device 200 performs targetdetection using two frames (similar to the step 916). The two framesinclude the current frame and a previous frame. The previous frame canbe the frame that immediately came before the current frame. Upondetecting the object in step 910, the electronic device 200 determines,in step 912, determines whether detected peak is the same for bothsingle-frame and two-frame processing. If detected peak is not the samefor both single-frame and two-frame processing, then the electronicdevice 200 uses the current frame for angle estimation (step 908).Alternatively, if the detected peak is the same for both single-frameand two-frame processing (as determined in 912), then the electronicdevice 200, in step 914, uses the two frames for angle estimation.

It is noted that if no object is detected in step 910 or step 916, theelectronic device 200 can notify the RF exposure engine 426 of FIG. 4B(such as described above in step 570 of FIG. 5A) that no objects aredetected indicating that there is no need to mitigate the RF exposurelevels.

The method 1000 of FIG. 10 describes a process for determining whetherto use a current single frame, a previous single frame, or both thecurrent and previous frames for angle estimation based on detectionstatus and detected target tap index. It is noted that the method 1000considers the current single-frame and the two-frame of the currentprocessing frame, but also the previous single-frame (the first part ofthe two-frame).

As used in FIG. 10 , the expression d_(cur) is the detection status of acurrent frame, p_(prev) is the detection status of a previous frame, andd₂ is the detection status of both the current and previous frame.Additionally, the expression p_(cur) is the tap index of the detectedobject of the current frame, p_(prev) is the tap index of the detectedobject of the previous frame, and p₂ is the is the tap index of the boththe current and previous frames. The previous frame can be the framethat immediately came before the current frame.

For example, when the current single-frame can detect the object (suchas when d_(cur) is true), the steps are the same as the embodimentdescribed FIG. 8 . The difference is when d_(cur) is false. In thiscase, the electronic device 200 checks the previous single-frame andfollow a similar process as for the current single frame. The rationalefor this is that if the object is not detected by the currentsingle-frame, it is likely that there is not much movement. Therefore,using the previous single-frame is better because using the two-frameswould likely just be an average over the noise for those pulsescorresponding to the current single-frame which could harm the SNR. Itis noted that for the case of estimating using the previoussingle-frame, the electronic device 200 could just output the angleestimated in the previous processing frame and there is no need to redothe estimation. Further extension by using the amplitude instead of thetarget tap index or using both amplitude and the target tap index couldbe done similarly as in the embodiments described above.

In step 1002, the electronic device 200 determines whether the object isdetected using the current frame or two frames (the current frame andframe that preceded the current frame). If the object is not detected ineither of the current frame or the two frames, then the electronicdevice 200, in step 1004, determines that no object is detected. Theelectronic device 200 can notify the RF exposure engine 426 of FIG. 4B(such as described above in step 570 of FIG. 5A) that no objects aredetected indicating that there is no need to mitigate the RF exposurelevels.

Alternatively, if the electronic device 200 determines that an object isdetected in either of the current frame or two frames (the current frameand the previous frame), then in step 1006, the electronic device 200determines whether an object is detected from the current frame (whetherd_(cur) is true). If the electronic device 200 determines that an objectis detected from the current frame, then in step 1008, the electronicdevice 200 determines whether detected peak is the same for bothcurrent-frame and two-frame processing. If detected peak is not the samefor both current-frame and two-frame processing, then the electronicdevice 200 uses the current frame for angle estimation (step 1010).However, if the detected peak is the same for both current-frame andtwo-frame processing (as determined in step 1008), then the electronicdevice 200, in step 1012, uses the two frames for angle estimation.

If the electronic device 200 determines, in step 1006, that no object isdetected from the current frame, then in step 1014, the electronicdevice 200 determines whether an object is detected from the previousframe. If the object is not detected in the previous frame (asdetermined in step 1014) then the electronic device 200, in step 1012,uses the two frames for angle estimation. Alternatively, if the objectis detected in the previous frame (as determined in step 1014) then theelectronic device 200, in step 1016, determines whether detected peak isthe same for both previous-frame and two-frame processing. If detectedpeak is not the same for both previous-frame and two-frame processing,then the electronic device 200 uses the previous frame for angleestimation (step 1018). However, if the detected peak is the same forboth previous-frame and two-frame processing (as determined in step1016), then the electronic device 200, in step 1012, uses the two framesfor angle estimation.

It is noted that the methods 600, 700, 800, 900 and 1000 are describedwith respect to detecting a single object. These methods are not limitedto a single object. Rather, these methods can be used for each detectedobject.

Additionally, the methods of FIGS. 6 through 9 can be extended to morethan two frames, as shown in the method 1100 as illustrated in FIG. 11 .For example, FIG. 11 describes an example process of determining anumber of frames for angel estimation, to use up to k frames, where k isan integer.

In step 1102, the electronic device determines whether an object isdetected. If the object is not detected, then in step 1104, theelectronic device determines that no object is detected. The electronicdevice 200 can then notify the RF exposure engine 426 of FIG. 4B (suchas described above in step 570 of FIG. 5A) that no objects are detectedindicating that there is no need to mitigate the RF exposure levels.

If the object is detected (as determined in step 1102), the electronicdevice in step 1106, determines whether to use the current frame forangle estimation. If the electronic device 200 determines to use thecurrent frame for angle estimation, then in step 1108, the electronicdevice 200 uses the current frame for angle estimation. Alternatively,if the electronic device 200 determines to not use the current frame forangle estimation, then in step 1110, the electronic device 200determines whether to use the two frames for angle estimation. If theelectronic device 200 determines to use the two frames for angleestimation, then in step 1112, the electronic device 200 uses the twoframe for angle estimation. Alternatively, if the electronic device 200determines to not use the two frame for angle estimation, the processcontinues to determine a number of frames to use for angle estimation,similar to the steps 1106 and 1110. At step 1114, the electronic device200 determines whether to use the less frame than the maximum number offrames (k) for angle estimation. Upon determining to use one less thanthe maximum number of frames, then the electronic device uses thoseframes for angle estimation (step 1116). Alternatively, the electronicdevice uses all of the frames (k frames) for angle estimation (step1118).

Since there can be more than two frames, as described in the method 1100of FIG. 11 , the method 1200 of FIG. 12 describes an example where thenumber of frames, k, is set to three. It is noted that the method 1200expands the method 800 of FIG. 8 from two frames to three frames.

As used in FIG. 12 , the expression d_(cur) is the detection status of acurrent frame. The expression p_(cur) is the tap index of the detectedobject of the current frame The expression d₂ is the detection status oftwo frames (the current frame and frame that preceded the currentframe). The expression p₂ is the is the tap index when using two-frameprocessing (the current and second frame). the expressions d₃ and p₃ arethe detection status and the detected peak, respectively, when usingthree-frame processing.

In step 1202, the electronic device 200 determines whether the object isdetected using the current frame, two frames, or three frames. If theobject is not detected in any of the frames, then the electronic device200, in step 1204, determines that no object is detected. The electronicdevice 200 can notify the RF exposure engine 426 of FIG. 4B (such asdescribed above in step 570 of FIG. 5A) that no objects are detectedindicating that there is no need to mitigate the RF exposure levels.

Alternatively, if the electronic device 200 determines that an object isdetected in any of the frames, then in step 1206, the electronic device200 determines whether an object is detected from the current frame. Ifthe electronic device 200 determines that an object is detected from thecurrent frame, then in step 1208, the electronic device 200 determineswhether detected peak is the same for both single-frame and two-frameprocessing. If detected peak is not the same for both single-frame andtwo-frame processing, then the electronic device 200 uses the currentframe for angle estimation (step 1210).

If (i) the object is not detected in the current frame (as determined instep 1206) or (ii) the detected peak is the same for both single-frameand two-frame processing (as determined in step 1208), then theelectronic device 200, in step 1212, determines whether the object isdetected from the two frames (the current frame and the frame thatpreceded the current frame). If the object is not detected in the twoframes (as determined in step 1212) then the electronic device 200, instep 1214, uses the three frames for angle estimation.

Alternatively, if the object is detected in the two frames (asdetermined in step 1212) then the electronic device 200, in step 1216determines whether detected peak is the same for both two-frame andthree-frame processing. If detected peak is not the same for bothtwo-frame and three-frame processing, then the electronic device 200uses the two frames for angle estimation (step 1218). If detected peakis the same for both two-frame and three-frame processing, then theelectronic device 200 uses the three frames for angle estimation (step1218).

Although FIGS. 6-12 illustrates various examples for determining thenumber of frames to use for angle estimation various changes may be madeto FIGS. 6-12 . For example, while shown as a series of steps, varioussteps in FIGS. 6-12 could overlap, occur in parallel, or occur anynumber of times.

FIG. 13 illustrates an example method 1300 for modifying radio frequencyexposure levels based on an identified angle between an electronicdevice and an object according to embodiments of this disclosure. Themethod 1300 is described as implemented by any one of the client device106-114 of FIG. 1 , the electronic device 300 of FIG. 3A the electronicdevice 410 of FIG. 4A and can include internal components similar tothat of electronic device 200 of FIG. 2 . However, the method 1300 asshown in FIG. 13 could be used with any other suitable electronic deviceand in any suitable system, such as when performed by the electronicdevice 200.

In step 1302, the electronic device 200 transmits signals for objectdetection. The electronic device 200 can also receive the transmittedsignals that reflected off of an object via a radar transceiver, such asthe radar transceiver 270 of FIG. 2 . In certain embodiments, thesignals are radar. The signals are used to detect an object with regionsthat expand from the electronic device.

In certain embodiments, the radar signals can be transmitted in framesthat are separated by frame spacings. The transmission interval of aframe can be shorter than the frame spacing. The radar frames caninclude non-uniformly spaced radar pulses or uniformly spaced radarpulses.

In step 1304, the electronic device 200 detects an object using a singleradar frame or multiple radar frames based on the transmitted signals.The electronic device 200 can detect an object based on reflections ofthe transmitted signals. In certain embodiments, the object is a bodypart of the user. The electronic device 200 can distinguish a body partfrom an inanimate object based on motion. For example, the longer theframe (or multiple frames separated by frame spacings) the electronicdevice 200 can identify motion from a detected object. When motion ispresent the electronic device can classify the object as a body part forwhich RF exposure need to be monitored and adjusted. Alternatively, ifthe electronic device 200 does not detect motion, then the RF exposuredoes not need to be monitored and the electronic device does not need toidentify the angle between the object and the electronic device 200.

In step 1306, the electronic device 200 determines whether to use asingle radar frame or multiple radar frames for angle identification.The determination of whether to use a single radar frame or multipleradar frames for angle identification can be based on a detection statusof the body part using the single radar frame or the multiple radarframes. The determination of whether to use a single radar frame ormultiple radar frames for angle identification can be based on amagnitude of a peak amplitude of the radar signals, the magnituderepresenting whether the body part is stationary or moving. Thedetermination of whether to use a single radar frame or multiple radarframes for angle identification can be based on a change in location ofthe body part.

In step 1308, the electronic device 200 identifies the angle between theobject and the electronic device 200 using a single radar frame or themultiple radar frames. For example, based on a determination to use thesingle radar frame, the electronic device 200 identifies the anglebetween the object and the electronic device using a single radar frame.For another example, based on a determination to use the multiple radarframes, the electronic device 200 identifies the angle between theobject and the electronic device 200 using multiple radar frames.

In certain embodiments, the electronic device 200 identifies the anglebetween the object and the electronic device 200 using covariance valuesobtained based on averaging pulses within the one or more radar frames.

In step 1310, the electronic device 200 modifies the exposure level atone or more regions based on the identified angle that the object isrelative to the electronic device 200.

Although FIG. 13 illustrates example methods, various changes may bemade to FIGS. 13 . For example, while the method 1300 is shown as aseries of steps, various steps could overlap, occur in parallel, occurin a different order, or occur multiple times. In another example, stepsmay be omitted or replaced by other steps.

The above flowcharts illustrate example methods that can be implementedin accordance with the principles of the present disclosure and variouschanges could be made to the methods illustrated in the flowchartsherein. For example, while shown as a series of steps, various steps ineach figure could overlap, occur in parallel, occur in a differentorder, or occur multiple times. In another example, steps may be omittedor replaced by other steps.

Although the figures illustrate different examples of user equipment,various changes may be made to the figures. For example, the userequipment can include any number of each component in any suitablearrangement. In general, the figures do not limit the scope of thisdisclosure to any particular configuration(s). Moreover, while figuresillustrate operational environments in which various user equipmentfeatures disclosed in this patent document can be used, these featurescan be used in any other suitable system. None of the description inthis application should be read as implying that any particular element,step, or function is an essential element that must be included in theclaims scope.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. An electronic device comprising: a radartransceiver; and a processor operably connected to the radartransceiver, the processor configured to: transmit, via the radartransceiver, radar signals to detect an object within regions expandingfrom electronic device, detect the object using a single radar frame ormultiple radar frames from the radar signals, determine whether to usethe single radar frame or the multiple radar frames based on motion ofthe object for angle identification between the object and theelectronic device, identify the angle between the object and theelectronic device using (i) the single radar frame based on adetermination to use the single radar frame or (ii) the multiple radarframes based on a determination to use the multiple radar frames, andmodify radio frequency exposure levels at one or more of the regionsbased on the angle of the object relative to the electronic device. 2.The electronic device of claim 1, wherein: the object is a body part ofa user; and to determine to use the single radar frame or the multipleradar frames is based on at least one of: a detection status of the bodypart using the single radar frame or the multiple radar frames, amagnitude of a peak amplitude of the radar signals, the magnituderepresenting whether the body part is stationary or moving, or a changein location of the body part.
 3. The electronic device of claim 1,wherein the radar signals are transmitted in frames of a first timeduration that are separated by a frame spacing of a second timeduration, wherein the second time duration is longer than the first timeduration.
 4. The electronic device of claim 1, wherein the processor isfurther configured to identify the angle using covariance valuesobtained based on averaging pulses within one or more radar frames. 5.The electronic device of claim 1, wherein to determine to use the singleradar frame or the multiple radar frames to identify the angle, theprocessor is configured to: determine whether the object is detectedusing the single radar frame; in response to a detection of the objectusing the single radar frame, determine to identify the angle betweenthe object and the electronic device using the single radar frame; whenthe object is not detected using the single radar frame, detect theobject using the multiple radar frames; and in response to a detectionof the object using the multiple radar frames, determine to identify theangle between the object and the electronic device using the multipleradar frames.
 6. The electronic device of claim 1, wherein to determineto use the single radar frame or the multiple radar frames to identifythe angle, the processor is configured to: determine whether the objectis detected using the single radar frame; in response to a detection ofthe object using the single radar frame, compare a threshold to a peakamplitude of the single radar frame of the radar signals correspondingto the object; determine to identify the angle between the object andthe electronic device using the single radar frame based on a firstresult of the comparison; when the object is not detected using thesingle radar frame or based on a second result of the comparison, detectthe object using the multiple radar frames; and in response to adetection of the object using the multiple radar frames, determine toidentify the angle between the object and the electronic device usingthe multiple radar frames.
 7. The electronic device of claim 1, whereinto determine to use the single radar frame or the multiple radar framesto identify the angle, the processor is configured to: determine whetherthe object is detected using the single radar frame or the multipleradar frames; in response to a determination that the object is detectedusing the single radar frame or the multiple radar frames, determinewhether the object is detected using the single radar frame; in responseto a determination that the object is detected using the single radarframe, determine whether a tap index of the single radar frame matches atap index of the multiple radar frames; in response to a determinationthat (i) the tap index of the single radar frame matches the tap indexof the multiple radar frames or (ii) the object is not detected usingthe single radar frame, determine to identify the angle between theobject and the electronic device using the multiple radar frames; and inresponse to a determination that the tap index of the single radar framedoes not match the tap index of the multiple radar frames, determine toidentify the angle between the object and the electronic device usingthe single radar frame.
 8. The electronic device of claim 1, wherein todetermine to use the single radar frame or the multiple radar frames toidentify the angle, the processor is configured to: determine whetherthe object is detected using the single radar frame; in response to adetermination that the object is not detected using the single radarframe, detect the object using the multiple radar frames; in response toa detection of the object using the multiple radar frames, determine toidentify the angle between the object and the electronic device usingthe multiple radar frames; in response to a detection of the objectusing the single radar frame, compare a threshold to a peak amplitude ofthe single radar frame of the radar signals corresponding to the object;in response to the comparison generating a first result, determine toidentify the angle between the object and the electronic device usingthe single radar frame; in response to the comparison generating asecond result, detect the object using the multiple radar frames; inresponse to a detection of the object using the multiple radar framesbased on the second result, determine whether a tap index of the singleradar frame matches a tap index of the multiple radar frames; inresponse to a determination that the tap index of the single radar framematches the tap index of the multiple radar frames, determine toidentify the angle between the object and the electronic device usingthe multiple radar frames; and in response to a determination that thetap index of the single radar frame does not match the tap index of themultiple radar frames, determine to identify the angle between theobject and the electronic device using the single radar frame.
 9. Theelectronic device of claim 1, wherein: the single radar frame is acurrent radar frame, the multiple radar frames include the current radarframe and a previous radar frame; and to determine to use the singleradar frame or the multiple radar frames to identify the angle, theprocessor is configured to: determine whether the object is detectedusing the current radar frame or the multiple radar frames, in responseto a determination that the object is detected using the current radarframe or the multiple radar frames, determine whether the object isdetected using the current radar frame, in response to a determinationthat the object is detected using the current radar frame, determinewhether a tap index of the current radar frame matches a tap index ofthe multiple radar frames, in response to a determination that the tapindex of the current radar frame does not match the tap index of themultiple radar frames, determine to identify the angle between theobject and the electronic device using the current radar frame, inresponse to a determination that the object is not detected using thecurrent radar frame, determine whether the object is detected using theprevious radar frame, in response to a determination that the object isdetected using the previous radar frame, determine whether a tap indexof the previous radar frame matches the tap index of the multiple radarframes, in response to a determination that the tap index of theprevious radar frame does not match the tap index of the multiple radarframes, determine to identify the angle between the object and theelectronic device using the previous radar frame, and in response to adetermination that (i) the tap index of the current radar frame matchesthe tap index of the multiple radar frames, (ii) the object is notdetected using the previous radar frame, or (iii) the tap index of theprevious radar frame matches the tap index of the multiple radar frames,determine to identify the angle between the object and the electronicdevice using the multiple radar frames.
 10. The electronic device ofclaim 1, wherein: the single radar frame is a current radar frame; themultiple radar frames include the current radar frame and a number ofprevious radar frames; and to determine to use the single radar frame orthe multiple radar frames to identify the angle, the processor isconfigured to: in response to a determination that the object isdetected, determine whether to use the current radar frame to identifythe angle, in response to a determination to use the current frame,determine to identify the angle between the object and the electronicdevice using the current radar frame, in response to a determination tonot use the current frame, identify a number of the previous radarframes to identify the angle, and determine to identify the anglebetween the object and the electronic device using the current radarframe and the identified number of the previous radar frames, theidentified number of the previous radar frames directly precede thecurrent radar frame.
 11. A method comprising: transmitting radar signalsto detect an object within regions expanding from electronic device;detecting the object using a single radar frame or multiple radar framesfrom the radar signals; determining whether to use the single radarframe or the multiple radar frames based on motion of the object forangle identification between the object and the electronic device;identifying the angle between the object and the electronic device using(i) the single radar frame based on a determination to use the singleradar frame or (ii) the multiple radar frames based on a determinationto use the multiple radar frames; and modifying radio frequency exposurelevels at one or more of the regions based on the angle of the objectrelative to the electronic device.
 12. The method of claim 11, wherein:the object is a body part of a user; and determining to use the singleradar frame or the multiple radar frames is based on at least one of: adetection status of the body part using the single radar frame or themultiple radar frames, a magnitude of a peak amplitude of the radarsignals, the magnitude representing whether the body part is stationaryor moving, or a change in location of the body part.
 13. The method ofclaim 11, wherein the radar signals are transmitted in frames of a firsttime duration that are separated by a frame spacing of a second timeduration, wherein the second time duration is longer than the first timeduration.
 14. The method of claim 11, further comprising identifying theangle using covariance values obtained based on averaging pulses withinone or more radar frames.
 15. The method of claim 11, whereindetermining to use the single radar frame or the multiple radar framesto identify the angle, comprises: determining whether the object isdetected using the single radar frame; in response to a detection of theobject using the single radar frame, determining to identify the anglebetween the object and the electronic device using the single radarframe; when the object is not detected using the single radar frame,detecting the object using the multiple radar frames; and in response toa detection of the object using the multiple radar frames, determiningto identify the angle between the object and the electronic device usingthe multiple radar frames.
 16. The method of claim 11, whereindetermining to use the single radar frame or the multiple radar framesto identify the angle, comprises: determining whether the object isdetected using the single radar frame; in response to a detection of theobject using the single radar frame, comparing a threshold to a peakamplitude of the single radar frame of the radar signals correspondingto the object; determining to identify the angle between the object andthe electronic device using the single radar frame based on a firstresult of the comparison; when the object is not detected using thesingle radar frame or based on a second result of the comparison,detecting the object using the multiple radar frames; and in response toa detection of the object using the multiple radar frames, determiningto identify the angle between the object and the electronic device usingthe multiple radar frames.
 17. The method of claim 11, whereindetermining to use the single radar frame or the multiple radar framesto identify the angle, comprises: determining whether the object isdetected using the single radar frame or the multiple radar frames; inresponse to a determination that the object is detected using the singleradar frame or the multiple radar frames, determining whether the objectis detected using the single radar frame; in response to a determinationthat the object is detected using the single radar frame, determiningwhether a tap index of the single radar frame matches a tap index of themultiple radar frames; in response to a determination that (i) the tapindex of the single radar frame matches the tap index of the multipleradar frames or (ii) the object is not detected using the single radarframe, determining to identify the angle between the object and theelectronic device using the multiple radar frames; and in response to adetermination that the tap index of the single radar frame does notmatch the tap index of the multiple radar frames, determining toidentify the angle between the object and the electronic device usingthe single radar frame.
 18. The method of claim 11, wherein determiningto use the single radar frame or the multiple radar frames to identifythe angle, comprises: determining whether the object is detected usingthe single radar frame; in response to a determination that the objectis not detected using the single radar frame, detecting the object usingthe multiple radar frames; in response to a detection of the objectusing the multiple radar frames, determining to identify the anglebetween the object and the electronic device using the multiple radarframes; in response to a detection of the object using the single radarframe, comparing a threshold to a peak amplitude of the single radarframe of the radar signals corresponding to the object; in response tothe comparison generating a first result, determining to identify theangle between the obj ect and the electronic device using the singleradar frame; in response to the comparison generating a second result,detecting the object using the multiple radar frames; in response to adetection of the object using the multiple radar frames based on thesecond result, determining whether a tap index of the single radar framematches a tap index of the multiple radar frames; in response to adetermination that the tap index of the single radar frame matches thetap index of the multiple radar frames, determining to identify theangle between the object and the electronic device using the multipleradar frames; and in response to a determination that the tap index ofthe single radar frame does not match the tap index of the multipleradar frames, determining to identify the angle between the object andthe electronic device using the single radar frame.
 19. The method ofclaim 11, wherein: the single radar frame is a current radar frame, themultiple radar frames include the current radar frame and a previousradar frame; and determining to use the single radar frame or themultiple radar frames to identify the angle, comprises: determiningwhether the object is detected using the current radar frame or themultiple radar frames, in response to a determination that the object isdetected using the current radar frame or the multiple radar frames,determining whether the object is detected using the current radarframe, in response to a determination that the object is detected usingthe current radar frame, determining whether a tap index of the currentradar frame matches a tap index of the multiple radar frames, inresponse to a determination that the tap index of the current radarframe does not match the tap index of the multiple radar frames,determining to identify the angle between the object and the electronicdevice using the current radar frame, in response to a determinationthat the object is not detected using the current radar frame,determining whether the object is detected using the previous radarframe, in response to a determination that the object is detected usingthe previous radar frame, determining whether a tap index of theprevious radar frame matches the tap index of the multiple radar frames,in response to a determination that the tap index of the previous radarframe does not match the tap index of the multiple radar frames,determining to identify the angle between the object and the electronicdevice using the previous radar frame, and in response to adetermination that (i) the tap index of the current radar frame matchesthe tap index of the multiple radar frames, (ii) the object is notdetected using the previous radar frame, or (iii) the tap index of theprevious radar frame matches the tap index of the multiple radar frames,determining to identify the angle between the object and the electronicdevice using the multiple radar frames.
 20. A non-transitory computerreadable medium embodying a computer program, the computer programcomprising computer readable program code that, when executed by aprocessor of an electronic device, causes the processor to: transmitradar signals to detect an obj ect within regions expanding fromelectronic device; detect the object using a single radar frame ormultiple radar frames from the radar signals; determine whether to usethe single radar frame or the multiple radar frames based on motion ofthe object for angle identification between the object and theelectronic device; identify the angle between the object and theelectronic device using (i) the single radar frame based on adetermination to use the single radar frame or (ii) the multiple radarframes based on a determination to use the multiple radar frames; andmodify radio frequency exposure levels at one or more of the regionsbased on the angle of the object relative to the electronic device.